First impressions are important, but a final impression can be just as significant. Considering it will be the last of the seven nations for players to explore, Snezhnaya needs to learn from every region that has come before it. In the same way, since it is the home of the game's main villains, Snezhnaya's other playable characters should reflect this.
Of course, Snezhnaya doesn't need to make all of its characters associated with the Harbingers. In fact, they don't need to be antagonists in general. However, the Fatui Harbingers are some of the most popular characters in the game for a reason. Each of them is extremely distinct from one another, and this could inspire the next characters to join Genshin Impact's large roster.
Snezhnaya Could Be a Swan Song for Genshin Impact Character Design
Genshin Impact has a large number of playable characters, which somewhat explains why some designs may seem similar. If there is any time to break the game's previous conventions, it's Snezhnaya. Not only is the setting different from every previous region, it may be the last chance for developers to innovate on existing tropes.
Snezhnaya's climate is a simple example of a factor that could influence its characters' designs. Sumeru and Natlan both have arid regions, and the characters living there mostly reflect this in their clothing style. In contrast, Snezhnaya is the land of Cryo, and its freezing climate provides plenty of reasons for unique characters. Genshin Impact has had a problem with diversity in the past, and it's unlikely that Snezhnaya could completely fix this, but developers could always aim for more cultural accuracy.